Bowel Obstruction

In a bowel obstruction (intestinal obstruction), something prevents the contents of the intestines from passing normally through the digestive tract. The problem can occur inside or outside the intestine. Internally, a tumor or swelling can block the inside passageway of the intestine. Externally, the problem usually is some structural problem that pinches, compresses or twists a segment of bowel.

A bowel obstruction can occur in the small bowel (small intestine) or large bowel (large intestine or colon). Also, a bowel obstruction can be total or partial, depending on whether any intestinal contents can pass through the obstructed area.

In the small intestine, the most common causes of bowel obstruction are:

Adhesions — Adhesions are areas of tough, fibrous connective tissue that may develop on the outside of injured abdominal and pelvic organs as they heal. Adhesions often grow on the external surface of the small intestine after surgery, especially after gynecologic procedures, or after surgery involving the appendix or colon. In time, adhesions can lead to small-bowel obstruction by acting like constricting bands, pinching a portion of the small intestine closed from the outside. Adhesions also can grow between neighboring loops of intestine, binding the loops into abnormal configurations that limit the flow of intestinal contents. Adhesions are the most common cause of small-bowel obstruction in the United States, accounting for 50 percent to 70 percent of all cases.

Hernia — If there is a structural weakness in the wall of the abdomen, a portion of the small intestine may protrude through this weakened area, and appear as a lump under the skin. This protruding segment of intestine, called a hernia, can cause small-bowel obstruction if the intestine becomes trapped or tightly pinched at the point where it pokes through the abdominal wall. In extreme cases, the pinched intestine also may “strangulate,” meaning the blood supply is cut off. Hernias are the second most common cause of small-bowel obstruction in the United States, accounting for about 25 percent of all cases. Typically, hernias appear as lumps near the navel (umbilical hernia), between the navel and breastbone (ventral hernia), at the site of a healed surgical incision (incisional hernia), near the groin (inguinal hernia), or at the front of the upper thigh (femoral hernia).

Tumors — Cancerous tumors typically cause small-bowel obstruction either by pressing on the outside of the bowel and pinching it closed, or by growing within the wall of the intestine and slowly blocking its inner passageway. Cancerous tumors account for a small percent of all small-bowel obstructions. In most cases, the tumor does not originate within the small intestine itself. Instead, it is usually a cancer that has spread (metastasized) to the small bowel from another site in the colon, female reproductive tract, breast, lung or skin.

In the large intestine, the most common causes of bowel obstruction are:

Colorectal cancer — About half of all large-bowel obstructions are caused by colorectal cancer. Undiagnosed colon or rectal cancer may cause a gradual narrowing of the large intestine’s inner passageway. Usually patients experience intermittent constipation and narrow (pencil-thin) stools for a while before the bowel finally becomes obstructed.

Volvulus — Volvulus is an abnormal twisting of a segment of bowel around itself. This twisting motion typically produces a closed loop of bowel with a pinched base, leading to intestinal obstruction. In Western countries, volvulus is most common among people over age 65, and these patients often have a history of chronic constipation. Unlike obstruction from colorectal cancer, obstruction caused by volvulus generally causes symptoms that evolve quickly, usually within a couple days.

Diverticular disease — In the large bowel, diverticula are small, balloon-shaped pouches that protrude from the wall of the intestine. If diverticula become infected, a condition called diverticulitis, they eventually may heal and form areas of scar tissue called strictures. Over time, these strictures can narrow the passageway of the intestine gradually, usually causing a slow-onset form of intestinal obstruction that has a pattern similar to that seen with colorectal cancer.

Crampy abdominal pain, generally coming in intense waves that strike at intervals of five to 15 minutes and sometimes center either on the navel or between the navel and rib cage (Pain that becomes constant may be a symptom of bowel strangulation)

Nausea and vomiting

No gas passing through the rectum

A bloated abdomen, sometimes with abdominal tenderness

Rapid pulse and rapid breathing during episodes of cramps

Symptoms of large-bowel obstruction can include:

A bloated abdomen

Abdominal pain, which can be either vague and mild, or sharp and severe, depending on the cause of the obstruction

Constipation at the time of obstruction, and possibly intermittent bouts of constipation for several months beforehand

If a colon tumor is the cause of the problem, a history of some type of rectal bleeding (especially streaks of blood on the stool) or of pencil-thin stools

Diarrhea resulting from liquid stool leaking around a partial obstruction

To help establish the diagnosis, your doctor will ask you about any history of abdominal surgery, chronic constipation, rectal bleeding, diverticulitis or hernias. He or she then will perform a physical examination, including a digital rectal examination. Blood tests and X-rays of your abdomen also may be needed.

If your doctor suspects you have a large-bowel obstruction, he or she may use a colonoscope, a tube that is inserted through the rectum to view the lower intestine. If the obstruction is caused by a volvulus, the passing of this instrument into the bowel not only confirms the diagnosis, but also untwists the intestine and relieves the obstruction.

Symptoms of small-bowel obstruction and large-bowel volvulus tend to develop rapidly, often over a period of hours. However, large-bowel obstruction caused by colorectal cancer or diverticular disease may develop slowly. Some patients have mild symptoms for several weeks or months before seeing a doctor. Once the diagnosis is made, treatment begins immediately. With successful treatment, the obstruction is relieved.

You may be able to reduce your risk for some forms of bowel obstruction by modifying your diet and lifestyle. For example:

To help prevent colorectal cancer, eat a balanced diet low in fat with plenty of vegetables and fruits, don’t smoke, and see your doctor for colorectal cancer screening once a year after age 50.

To help prevent hernias, avoid heavy lifting, which increases pressure inside the abdomen and may force a section of intestine to protrude through a vulnerable area of your abdominal wall. If you develop an abnormal lump under the skin of your abdomen, especially near your groin or near a surgical scar, contact your doctor.

There is no proven way to prevent obstruction caused by diverticular disease, but some doctors believe that people with diverticular disease should follow a high-fiber diet and avoid foods that may become lodged in the diverticula, such as seeds and popcorn.

If you have a bowel obstruction, you will be treated in a hospital. A flexible, lubricated nasogastric tube (NG tube) will be inserted through your nose into your stomach to help remove excess gas from your stomach and intestines. You will be given fluids intravenously (through a vein) because you will not be allowed to eat or drink.

Partial small-bowel obstruction often improves within a few days, and the NG tube can be removed. At that point, you will be given sips of fluid. If this is tolerated, then a full liquid diet is given for a day followed by solid foods that are easy to digest. A complete bowel obstruction often requires surgery to correct or remove the cause of the obstruction (tumor, adhesions, stricture), repair the hernia, or fix the segment of intestine at risk of repeated volvulus. During this surgery, a segment of damaged or strangulated intestine also may be removed.

The prognosis depends on the cause of your bowel obstruction, your age, whether you have any other illnesses (especially heart, lung or kidney problems), and the timing of your treatment. Obstruction not associated with cancer has a very good prognosis, especially in otherwise healthy people.

Last revised: December 3, 2007by Gevorg A. Podosyan, Ph.D.

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.